Semiconductor device fabrication involves using a number of fabrication processes to build a desired device. Generally, a semiconductor device is fabricated on a semiconductor material referred to as a substrate by forming layers or components, selectively patterning formed layers, and selectively implanting dopants into layers and/or the substrate in order to achieve desired operational characteristics.
A common structure that is fabricated in semiconductor devices is a shallow trench isolation (STI) region formed in a substrate. The STI region serves to electrically isolate multiple active devices (e.g., transistors) so that they do not interfere with each others' operations. Generally, an STI region is formed in/on a device by selectively etching a shallow trench between components or devices, filling the shallow trench with oxide, and then planarizing the device to substantially remove portions of the fill oxide from a surface of the device while leaving the fill oxide within the etched shallow trench.
Typically, formation of STI regions employs forming an etch stop layer prior to etching the shallow trenches. The etch stop layer is selectively formed (deposited and patterned) in non-trench regions and is comprised of a material, such as nitride, that is substantially resistant to a planarization process being employed. A trench oxide fill process is then performed that deposits oxide into the shallow trenches. During the fill process, clipping and/or damage to the etch stop layer can occur. For relatively larger devices, this clipping and/or damage of the etch stop layer may not be a problem. However, as semiconductor device sizes continue to decrease, so does the size and/or amount of etch stop material. If plasma based processes are used to fill the trench, then is necessary to increase the plasma power to be able to completely fill the trench. This increase in power produces an increase in etch stop layer clipping. If a minimal amount of etch stop material is not present, the CMP planarization process can damage underlying regions and the filled trenches.
What is needed are systems and methods that mitigate clipping and/or damage to etch stop layers and facilitate shallow trench isolation region fabrication.